There are families of aluminum alloys that are prepared in the form of sheets, bars, tubes, or the like for subsequent working and shaping into articles of manufacture. For example, the Aluminum Alloys of the 2xxx, 5xxx, and 6xxx families contain silicon, iron, copper, manganese, magnesium, and zinc as alloying constituents in varying specified amounts in the respective commercial family compositions. These alloying constituents are employed to impart desired physical and corrosion resistant properties to the respective alloys. Many of these alloys also contain small amounts of chromium and titanium. Chromium and titanium are often employed to affect grain size in the wrought aluminum alloy material and thus its ductility and strength.
These aluminum alloys are widely used in metal forming operations in the manufacture of many products. Sheets, bars, and tubes can be worked at ambient factory temperatures by stamping, bending, and the like into many desired shapes. However, the wrought starting shapes do have forming limitations. For example, AA5xxx, non-heat-treatable aluminum and magnesium-containing alloys are normally used for high formability sheet forming applications but are often difficult to extrude. AA6xxx alloys are age hardenable aluminum, magnesium and silicon-containing alloys which are strong in finished form but have lower formability than the AA5xxx alloys. It is an object of this invention to improve the formability of such aluminum alloys using small amounts of chromium and thermomechanical processing in the preparation of the wrought starting material for further shaping.